The Importance of Feeding Newborn Calves Colostrum
It is known that the transfer of immunoglobulin across the placenta to the developing bovine foetus is minimal, so bovine neonates are born essentially agammaglobulinemic (Brambel, F. W. R. (1970), p 201-365 in Frontiers in Biology. Vol. 18, A. Neuberger and E. L. Tatum, ed. North Holland Publ. Co., Amsterdam, The Netherlands; Kruse, V (1970). Anim. Prod. 12:619-626). Given this fact, it is vital that newborn calves can acquire passive immunity from the immunoglobulin contained in the colostrum of the dam. Certainly, Penhale et al have concluded that the most important factor in resistance to infections at this early stage in the calf's life is its level of IgG (Penhale et al., (1970) Br. Vet. J. 126:30-37), and Rea et al have reported that a mortality risk is associated with calves with IgG concentrations of less than 5 g/L. (Rea et al., (1996) JAVMA. 28:2047-2049). Certainly, calf mortality is a significant economic problem to the farming industries, with high mortality rates within the first week after birth (Wells et al., (1996) Prev. Vet. Med 29:9-19).
It has also been demonstrated that the feeding of colostrum to newborn calves is associated with more efficient weight increases of the calves. Pedersen et al. (2000) have examined populations of calves fed either colostrum or milk replacer and observed that those calves receiving colostrum at birth gained weight in the first week after birth, compared to calves on milk replacer which lost weight during the same period (Pedersen et al., (2000), J. Dairy Sci 83:2829-2833). Pedersen et al postulate that this difference could have been caused by either the high nutrient density in the colostrum and/or by the enhancing of the calves' immune device by the calves acquiring immunoglobulin from the colostrum. Certainly, the calves fed colostrum had a higher plasma immunoglobulin concentration after 24 and 48 hours than those fed milk replacer.
Advantages of using an esophageal feeder to deliver colostrum to newborn calves Passive immunization of calves is most efficient immediately after birth, and ceases by about 24 hours after birth (Deutsch et al., (1983) in Veterinary medicine, 6th ed. 11907-1296, pub. Bailiere Tindall, London), thus it is important for the calf to receive enough colostrum within this short time. However, suckling calves often consume only small amounts of colostrum (Gay (1983) Proc. Fourth Int. Symp. Neonatal Diarrhea. Unir. Saskatchewan. 346-364), and although monitoring of the quantity of colostrum consumed can be done using a nipple bottle, the calves cannot be force-fed enough colostrum using this method. Thus, force-feeding of calves using an esophageal feeder during the critical time-period immediately after birth may ensure that the calves consume enough colostrum to gain sufficient passive immunity.
Additionally, it has been demonstrated for newborn lambs that the likelihood for disease and death is significantly decreased from force-feeding with colostrum using an esophageal feeder during the first 24 hours of life and it is likely that other animals may benefit in a similar way from early feeding of colostrum.
Use of an esophageal feeder is also a relatively quick process and as it requires only a short period of time on behalf of the operator it is cost effective.
Problems Associated with Current Esophageal Feeders
There are problems associated with the esophageal feeders known to those skilled in the art. It is desirable that while using these types of device, the operator should have both hands free, e.g. as in the case of when using these devices with calves, it is desirable to “minimize the calf being able to move and toss its head . . . (as) . . . this can cause injury”. (Frank, R., Dairy Herd Management, October 1997, pub. Vance Publishing Corp.). In addition, farmers may be concerned about “accidentally placing the tube down the trachea”, and it is suggested that to solve this problem the operator has “someone else hold the bag of milk. This way you can use both of your hands to feel the tube moving into the esophagus”. (Frank, R., Dairy Herd Management, October 1997, pub. Vance Publishing Corp.) However, this is clearly a labour-intensive process and it is clearly desirable and more cost-effective for an operator of an esophageal feeder to work alone. Thus, a feeding device carried by the operator in a way allowing his hands to be free, whilst still allowing the device to be easily accessible, is highly desirable. Such a device must also be easily sanitized, to prevent infection of the young calves.
Certainly, there have been some attempts at meeting some of these needs in animal feeding devices: the large plastic bottle used with some drench gun devices can be strapped to the farmer's back, however this bottle is reusable and so there is a chance of infection of the animal from an inadequately sanitised bottle. Furthermore these types of bottle are too bulky and heavy to transport easily. Flexible plastic bags to contain the colostrum in esophageal feeding devices have also been documented, however not in combination with a “hands-free” method of transportation: at best these inventions incorporate a mechanism for hanging the colostrum bag onto a hook, which is inconvenient to do before the feeder is properly inserted into the esophagus as this then restricts the operator's range of movement.